Method for delegated key sharing for digital car key system

ABSTRACT

A system and method for sharing a digital key for a vehicle. The system includes a first digital key device having a digital key stored thereon, a second digital key device, and a vehicle server. The first digital key device sends a request to the vehicle server for a key sharing session. The vehicle server commences a key sharing session in response to the request. The first digital key device shares the digital key to a second digital key device. The vehicle server ends the key sharing session.

INTRODUCTION

The subject disclosure relates to methods for sharing digital keys usedto operate vehicles and, in particular, a system and method ofpreventing authorizing use of a digital key from sharing conflicts.

With the advent of digital key technology, a digital key can be storedin an electronic digital key device, such as a smartphone, etc. and usedto operate a vehicle. A digital key is an encoded data or datastructure. A person possessing the digital key device brings the digitalkey device into proximity with the vehicle and the digital key is sentfrom the digital key device to the vehicle to unlock the vehicle. Whenthe digital key matches a copy of the digital key stored at the vehicle,the vehicle can be used by the person. The digital key can also beshared from one person to another person by transmitting a copy of thedigital key from the digital key device to another key device which ispossessed by the other person. A potential for sharing conflict occurswhen multiple copies of a digital key are stored on multiple digital keydevices. Accordingly, it is desirable to provide a method for sharing adigital key without creating sharing conflicts amongst multiple digitalkey devices.

SUMMARY

In one exemplary embodiment, a method of sharing a digital key for avehicle is disclosed. A request for a key sharing session is sent from afirst digital key device to a vehicle server, the first digital keydevice having a digital key stored thereon. The key sharing session iscommenced at the vehicle server. The digital key is shared from thefirst digital key device to a second digital key device. The key sharingsession is ended at the vehicle server.

In addition to one or more of the features described herein, the methodfurther includes granting, via the vehicle server, exclusive rights tothe first digital key device to share the digital key during the keysharing session. The method further includes sharing the digital key bytracking active entitlements for the digital key. In an embodiment inwhich the first digital key device is a delegate device, the methodfurther includes registering the digital key stored on the delegate keydevice at the vehicle. The digital key stored on the delegate deviceincludes a certificate including an owner signature from an owner devicethat entitles the delegate device to share the digital key. Registeringthe digital key stored on the delegate device at the vehicle furtherincludes verifying the owner signature from the digital key. In anembodiment, the method further includes establishing a digital twin ofthe first digital key device at a twin server and sharing the digitalkey using the digital twin at the twin server. The method furtherincludes sending a key sharing request from the twin server to the firstdigital key device, creating a shared digital key at the first digitalkey device and sending the shared digital key from the first digital keydevice to the twin server, wherein the twin server sends the shareddigital key to the second digital key device. The method furtherincludes using the shared key at the second digital key device toperform an operation at the vehicle.

In another exemplary embodiment, a system for sharing a digital key fora vehicle is disclosed. The system includes a first digital key devicehaving a digital key stored thereon, a second digital key device, and avehicle server configured to commence a key sharing session in responseto a request from the first digital key device and to end the keysharing session; wherein the first digital key device shares the digitalkey to the second digital key device during the key sharing session.

In addition to one or more of the features described herein, the vehicleserver is configured to grant exclusive rights to the first digital keydevice to share the digital key during the key sharing session. Thevehicle server is configured to track active entitlements for thedigital key. In an embodiment, the first digital key device is adelegate device, and the vehicle server is configured to register thedigital key stored on the delegate device at the vehicle. The digitalkey stored on the delegate device includes a certificate including anowner signature from an owner device that entitles the delegate deviceto share the digital key. The vehicle is configured to register thedigital key stored on the delegate device by verifying the ownersignature from the digital key. In an embodiment, the system furtherincludes a twin server configured to establish a digital twin of thefirst digital key device and share the digital key using the digitaltwin. The twin server is configured to send a key sharing request to thefirst digital key device and the first digital key device is configuredto create a shared digital key and send the shared digital key to thetwin server in response to the key sharing request, wherein the twinserver sends the shared digital key to the second digital key device.The second digital key device is configured to use the shared key toperform an operation the vehicle.

The above features and advantages, and other features and advantages ofthe disclosure are readily apparent from the following detaileddescription when taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features, advantages and details appear, by way of example only,in the following detailed description, the detailed descriptionreferring to the drawings in which:

FIG. 1 shows a communication network suitable for operating a vehicleusing a digital key, in an illustrative embodiment;

FIG. 2 shows a communication diagram for sharing a key when there aremultiple key owners, such as shown in the communication network of FIG.1;

FIG. 3 illustrates a key sharing network that includes an owner device,one or more delegate entities and one or more vehicle user devices;

FIG. 4 shows a communication diagram that allows a delegate entity toremotely register its digital key at a vehicle;

FIG. 5 shows a network enabling an owner device or an owner device withits supporting back office server to share its digital key using a twinserver;

FIG. 6 shows a communication diagram for enrolling the delegate entityat a twin server to facilitate the sharing of a digital key, in anillustrative embodiment; and

FIG. 7 shows a communication diagram for key sharing using the twinserver once the delegate entity has been enrolled.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, its application or uses.

FIG. 1 shows a communication network 100 suitable for operating avehicle 102 using a digital key, in an illustrative embodiment. Thecommunication network 100 includes the vehicle 102, a vehicle server104, and multiple digital key devices. The vehicle server 104 can be aremote server or a cloud server and is generally an Original EquipmentManufacturer (OEM) server. The multiple digital key devices include afirst owner device 106 and a second owner device 108, for illustrativepurposes, as well as a vehicle user device 110. An owner device isgenerally an original owner and is established as such by having itsdigital key registered at the vehicle 102 upon purchase of the vehicle.A digital key device is generally a portable device and can be carriedto and from the vehicle 102 by a person or user.

For illustrative purposes, first owner device 106 is shown with variousoperating components. The first owner device 106 can be an electronicdevice, including but not limited to a smartphone, a tablet, or otherelectronic device. The first owner device 106 includes a processor 112and a memory 114, such as a solid-state memory. The digital key 116 canbe stored at the memory 114 and accessed by the processor 112 for use.The first owner device 106 further includes a communication port 118 forsending and receiving the digital key 116 or a copy of the digital keyto and from other devices. To unlock and operate the vehicle 102, anowner (also referred to herein as “first owner”) of the first ownerdevice 106 approaches the vehicle 102 to allow a communication betweenthe first owner device 106 and the vehicle 102. The digital key is thentransmitted from the first owner device 106 to the vehicle 102. Uponreceiving the digital key from the first owner device 106, a vehicleprocessor 120 at the vehicle 102 uses cryptographic algorithms tocompare the digital key to a stored key and allow operation of thevehicle by the first owner when the digital key matches the stored key.The vehicle server 104 can also transmit its copy of the digital key tothe vehicle 102 to unlock and operate the vehicle. The second ownerdevice 108 and the vehicle user device 110 include the components shownwith respect to the first owner device 106, although this is notspecifically illustrated.

The vehicle server 104, first owner device 106 and second owner device108 each store a copy of a digital key. In addition, a copy of thedigital key can be stored at a user device that has the same sharingcapabilities as the first owner device 106 through authorization by thefirst owner device. Such user device can be referred to herein as a“delegate device”. The vehicle user device 110 does not have its owncopy of the digital key. However, either of the first owner device 106,the second owner device 108 or delegated device can share its copy ofthe digital key with the vehicle user device 110 using the methodsdisclosed herein.

A device having a digital key means that the device stores a digital keypair including a private key and a public key. The device may also havea signature from the owner to authenticate its right to operate thevehicle by the owner. When a first device shares its digital key with asecond device, the second device stores a certificate that includes itsown public key and a copy of the signature generated by the private keyof the first device. Therefore, the second device obtains theauthorization from the first device after the digital key has beenshared.

A digital key is an encoded electronic data structure that can be usedto lock or unlock a vehicle. The digital key can include a certificateindicating authorization from an owner of the digital key to a selectedindividual. Each digital key can also include an associated entitlementor list of privileges allowed the digital key device or its owner. Forexample, one digital key device can be entitled to lock and unlock thevehicle. Another digital key device can be entitled to lock and unlockthe vehicle as well as to turn on the vehicle and drive. In anotherexample, the digital key device can be entitled to operate only during aselected time frame or time frames. For example, one owner can beallowed to operate the vehicle during weekdays while another user may beallowed to operate the vehicle from noon to 4 p.m. on an assigned day.Thus, the level of entitlement determines the types of operations thatcan be performed at the vehicle, such as, but not limited to, lockingand unlocking, driving the vehicle, time periods in which one can drivethe vehicle, parental supervision operations, sharing the digital key,etc.

The vehicle 102 includes a vehicle processor 120 that stores aregistered copy of the digital key. When a digital key device, such asthe first owner device 106 or the vehicle user device 110, is broughtinto communicative proximity of the vehicle 102, the vehicle processor120 reads the digital key stored thereon, runs a cryptographic algorithmto compare the digital key of the digital key device with the registeredcopy of the digital key and allows the user access to the vehicle oncethe registered copy matches the read digital key of the digital keydevice.

The methods disclosed herein provide a method of sharing keys thatavoids conflicts and ensures consistency of key sharing privileges andentitlements. Key sharing sessions are set up to provide a systematickey sharing process based on a specific key sharing topology.

FIG. 2 shows a communication diagram 200 for sharing a key when thereare multiple key owners, such as shown in the communication network 100of FIG. 1. The process illustrated in the communication diagram 200allows the multiple key owners to share their respective keys withoutcreating sharing conflicts. Communication is shown between the membersof the communication network 100, namely the first owner device 106(Device A), the vehicle server 104, the vehicle user device 110 and thesecond owner device 108 (Device B). The first owner device 106 can be adigital key device or a digital key device with its supporting backoffice. Similarly, the second owner device 108 can be a digital keydevice or a digital key device with its supporting back office and thevehicle user device 110 can be a digital key device or a digital keydevice with its supporting back office.

The communication diagram 200 illustrates the first owner device 106sharing its key with the vehicle user device 110 without creating asharing conflicted via the second owner device 108. The second ownerdevice can represent a second owner device or a user device that isauthorized by the first owner device to share its digital key. The firstowner device 106 begins by sending a synchronization request(communication signal 202) to the vehicle server 104 to establish a keysynchronization session. The vehicle server 104 responds by sending asecure session signal (communication signal 204) back to the first ownerdevice 106.

The first owner device 106 then sends a list of entitlements(communication signal 206) to the vehicle server 104. The list ofentitlements is a set of entitlements known by the first owner device106 with respect to the vehicle 102. The vehicle server 104 responds bysending a list of active entitlements (communication signal 208) for thevehicle to the first owner device 106. The first owner device 106 doesnot necessarily know all the active entitlements before thiscommunication. The list of active entitlements can form a schedule ofsharing entitlements for the vehicle. The first owner device 106 thenreviews the list of active entitlements on the schedule and generates asharing entitlement (box 210) that does not conflict with the existingactive entitlements on the schedule.

The first owner device 106 then sends a request (communication signal212) for a key sharing session to the vehicle server 104. Upon receivingthe request, the vehicle server 104 creates a locked session (box 214)for the first owner device 106. The locked session (box 214) allows thefirst owner device 106 to share its digital key with the vehicle userdevice 110 without being interrupted by another owner device.

For illustrative purposes, the second owner device 108 is shown sendinga request (communication signal 216) for a key synchronization sessionafter the locked session (box 214) has already been created. Since thefirst owner device 106 and the vehicle server 104 are in a lockedsession, the vehicle server 104 sends a busy signal (communicationsignal 218) back to the second owner device 108.

Once the locked session (box 214) has been created, the first ownerdevice 106 can share its digital key with the vehicle user device 110.The vehicle server 104 sends a sharing session signal (communicationsignal 220) to the first owner device 106 indicating that the lockedsession has been created. The first owner device 106 then sends asharing URL (communication signal 222) to the vehicle user device 110.The URL can have information attached. The vehicle user selects the URLto redeem the key. Once the URL is selected, the vehicle user device 110sends a redemption request (communication signal 224) for the shared keyto the vehicle server 104. The first owner device 106 or vehicle server104 then creates a sharing key (box 226) for the vehicle user device110.

The vehicle user device 110 then sends a track key signal (communicationsignal 228) to the vehicle server 104. The track key signal includes theauthorization of the vehicle user device 110. The vehicle server 104reviews and validates the authorization of the vehicle user device 110(box 230). The vehicle server 104 then validates the entitlement of thevehicle user device 110 (box 232) to be certain that there are noconflicts with other owners or user devices. The vehicle server 104 thenunlocks the session (box 234) and sends notifications (communicationsignals 238 and 236) to the vehicle user device 110 and the first ownerdevice 106, respectively, that the tracking session has ended. As shownfor illustrative purposes, the second owner device 108 can now request akey synchronization request (communication signal 240) to the vehicleserver 104 without receiving a busy signal.

As shown in FIG. 2, sharing can be performed between an owner device anda vehicle user device without sharing conflicts. However, a key networkcan also include an intermediate device between the owner device andvehicle user device. The intermediate device, also referred to as adelegate device, can receive a copy of the digital key from the ownerdevice and as well as an entitlement, bestowed on it by the ownerdevice, to share its copy of the digital key with another device, suchas the vehicle user device.

FIG. 3 illustrates a key sharing network 300 that includes an ownerdevice, one or more delegate entities and one or more vehicle userdevices. The one or more delegate entities can be a delegate server 304(or a server having delegate entitlements) or a delegate device 306 (ora digital key device having delegate entitlements). The owner device 302can share the digital key with the delegate entities. A digital keystored on a delegate entity is referred to herein as a delegate key. Thedelegate key also has the same entitlements as the digital key as wellas sharing privileges. Thus, the delegate entities can perform anoperation to use its delegated key to share a digital key with a vehicleuser, using the methods disclosed herein.

The owner device 302 stores a digital key pair that consists of aprivate digital key (e.g. A.sk) and a public key (e.g., A.pk) where thepublic key is registered with the vehicle 102. When the owner device 302shares its digital key with the delegate server 304. The delegate server304 stores a certificate including a public key (B.pk) and a signaturesigned by the private key (A.sk) of owner device 302, whichauthenticates the public digital key (B.pk). Similarly, the owner device302 can share its digital key with the delegate device 306 which thenstores a certificate including a public key (C.pk) and a signaturesigned by the private key (A.sk) of the owner device 302, whichauthenticates the public digital key (C.pk).

The delegate server 304 is shown sharing its digital key to a firstvehicle user device (e.g., P2P vehicle user device 308). The delegateserver 304 shares its digital key with the P2P vehicle user device 308by providing a certificate that includes the public key (D.pk) of theP2P vehicle user device 308 and a signature from the private key (B.sk)of the delegate server 304. Similarly, the delegate device 306 is shownsharing its digital key to a second vehicle user device (e.g., friendvehicle user device 312) by providing a certificate that includes thepublic key (E.pk) of the friend vehicle user device 312 and a signaturefrom the private key (E.pk) of the delegate device 306. The eventualvehicle user device therefore includes a digital key with a chain ofcertificates extending back to the owner device 302, which allows thevehicle to verify the digital key. In order for either of the delegateentities (i.e., delegate server 304, delegate device 306) to share itsdelegate key, it needs to register its delegate key with the vehicle 310or the vehicle 310 needs to verify the chain of the certificates.

FIG. 4 shows a communication diagram 400 that allows a delegate entity402 to remotely register its digital key at a vehicle 406. Thecommunication diagram 400 includes the delegate entity 402, a vehicleserver 404 and the vehicle 406.

The delegate entity 402 sends a remote registration request(communication signal 408) to the vehicle server 404. The vehicle server404 responds by establishing a secure link (communication signal 410)with the delegate entity 402. The delegate entity 402 then sends itsdelegate key certificate (communication signal 412) to the vehicleserver 404. Each delegate key includes a key certificate that shows achain back to the owner device 302, FIG. 3. The key certificate includesa chain of certificate. When the owner creates the delegate keycertificate, the owner device signs the delegate key, thereby providinga means for authenticating the delegate key certificate.

The vehicle server 404 extracts the owner key certificate from thedelegate key certificate (box 414). The vehicle server 404 then verifiesthe owner key certificate and the entitlement allowed to the delegateentity 402 (box 416).

Once the owner key certificate and the entitlement of the delegatedevice have been verified, the vehicle server 404 sends a notification(communication signal 418) to the delegate entity 402 to let thedelegate entity 402 know that a registration session has begun. Thevehicle server 404 then sends a request (communication signal 420) toestablish a secure link with the vehicle 406. The vehicle server 404then sends the delegate key certificate (communication signal 422) tothe vehicle 406 for installation at the vehicle 406.

The vehicle already has a copy of the owner certificate. The vehicle 406verifies (box 424) the owner signature from the delegate keycertificate. The vehicle then verifies (box 426) the entitlements of thedelegate, including the entitlement of the delegate to share its digitalkey. The vehicle 406 then stores (box 428) the delegate key. Once thedelegate key is stored at the vehicle 406, the vehicle sends a successsignal (communication signal 430) to the vehicle server 404, which thensends a notification (communication signal 432) to the delegate entity402 that the delegate key has been installed at the vehicle 406. Thedelegate entity 402 is now able to share its delegate key with a vehicleuser device (box 434).

FIG. 5 shows a network 500 enabling an owner device 502 or an ownerdevice with its supporting back office server to share its digital keyusing a twin server 506. The network 500 includes the owner device 502,a vehicle server 504, the twin server 506 and a delegate entity 508. Thedelegate entity can be a delegate server 510 (e.g., a fleet managementserver) or a delegate device 512, in various embodiments. The twinserver 506 is a server that stores the digital twin, a virtual copy ofthe owner device 502 or of the software of the owner device 502. Duringthe sharing process, a delegate entity 508 can be enrolled at the twinserver 506 as an intermediary device. The twin server 506 includes aserver interface 514 for communication with the delegate entity 508 aswell as a digital twin 516 and an owner user authentication module 518.The twin server 506 communicates with the owner device 502 in order tocreate the digital twin 516 of the owner device 502 or the software ofthe owner device 502. The delegate entity 508 then establishes rights toaccess the digital twin through the twin server.

FIG. 6 shows a communication diagram 600 for enrolling the delegateentity 508 at a twin server to facilitate the sharing of a digital key,in an illustrative embodiment. The owner device 502 establishes asession with the twin server 506 to allow the delegate entity 508 toenroll at the twin server 506. To set up a twin session, the ownerdevice 502 establishes a secure link (communication signal 602) with thevehicle server 504, which then establishes a secure link (communicationsignal 604) with the twin server 506. The owner device 502 then sends asession request (communication signal 606) to the vehicle server 504,which establishes a twin session with the twin server 506 (communicationsignal 608). The twin server 506 creates a digital twin instance of theowner device 502 with a pair of keys for the digital twin instance(twin.pk and twin.sk) (box 610). The twin server 506 then sends a twinsession confirmation (communication signal 612) to the vehicle server504. The twin session confirmation includes the twin instance public key(twin.pk). The vehicle server 504 forwards the twin session confirmationand twin instance public key (twin.pk) (communication signal 614) to theowner device 502. The owner device uses its private key (owner.sk) tosign a certificate for the twin's public key and send it back(communication signal 616) to the vehicle server 504. The vehicle server504 then forwards the certificate back to the twin server (communicationsignal 618), indicating the establishment of the twin session.

The owner device 502 then sends a message (communication signal 620) tothe delegate entity 508 to notify the delegate entity 508 that a sessionhas been opened to allow it to be enrolled at the twin server 506. Themessage includes the owner.pk, the twin.pk and a delegate userID. Thedelegate entity 508 receiving the message has an already establisheddelegate userID and delegate password, delegate.pk and delegate.sk. Onreceiving the enrollment message from the owner device 502, the delegateentity 508 performs a user authentication (box 622), if necessary, toallow the delegated userID be used.

The delegate entity 508 then sends an enrollment signal (communicationsignal 624) to the twin server 506. The twin server 506 notifies thevehicle server 504 of the enrollment (communication signal 626) and thevehicle server 504 sends an acknowledgment (communication signal 628)back to the twin server 506. The twin server 506 stores the owner.pk andthe delegate.pk and creates a link session for the delegate entity (box630). The twin server 506 further uses its private key (twin.sk) to signa certificate for the delegate entity's public key (delegate.pk).Enrollment confirmations (communication signals 632 and 634), includingthe signed certificate, are sent from the twin server 506 to thedelegate entity 508 and vehicle server 504, respectively, to confirmenrollment of the delegate entity 508. The vehicle server 504 forwardsthe enrollment confirmation (communication signal 636) to the ownerdevice 502. When the enrollment process has been completed, the delegateentity 508 can control the twin instance on the twin server 506.

FIG. 7 shows a communication diagram 700 for key sharing using the twinserver 506 once the delegate entity 508 has been enrolled. The delegateentity 508 shares the delegate key to a vehicle user device 110 via thetwin server 506. At the back end, the twin server 506 can synchronizewith the owner device.

The delegate entity 508 sends a sharing request (communication signal702) to the twin server 506, which sends a sharing session request(communication signal 704) to the vehicle server 504. The twin server506 can also synchronize the session request with the owner device 502(communication signals 706 a and 706 b) through an established securecommunication channel. The vehicle server 504 establishes the session(communication signal 708) with the twin server 506. The twin server 506can also synchronize the established session with the owner device 502(communication signals 710 a and 710 b).

The twin server 506 sends a sharing URL (communication signal 712) tothe vehicle user device 110 to allow the vehicle user device to receivea copy of the delegate key. The sharing of the URL is synchronized withthe owner device (communication signals 714 a and 714 b). The vehicleuser device 110 redeems the URL (communication signal 716) at thevehicle server 504. The remote server sends notification signals to thetwin server 506 (communication signal 718) and to the vehicle userdevice 110 (communication signal 720) to verify that a sharing sessionhas been created. The twin server 506 can also synchronize the creationof the sharing session with the owner device 502 (communication signals722 a and 722 b).

The twin server 506 sends a key creation request (communication signal724) to the vehicle user device 110, synchronizing this key creationrequest with the owner device 502 (communication signals 726 a and 726b). The vehicle user device 110 sends a signed request back to the twinserver 506 (communication signal 728). The twin server forwards thesigned request to the owner device 502 (communication signal 730). Theowner device 502 signs a shared digital key (box 732) and shares thedigital key with the twin server 506 (communication signal 734). Thetwin server 506 shares the digital key with the vehicle user device 110(communication signal 736) and synchronizes with the owner device 502 toallow the owner device to know that the digital key is now shared withthe vehicle user device 110 (communication signals 738 a and 738 b).

The vehicle user device 110 imports the shared key (box 740) and sends atrack key signal (communication signal 742) to the vehicle server 504,which sends a notification (communication signal 744) to the twin server506. A notification (communication signal 744) is sent from the vehicleserver 504 to the twin server 506, and a notification (communicationsignal 746) is sent from the vehicle server 504 to the vehicle userdevice 110. The key tracking state can be synchronized with the ownerdevice 502 (communication signals 748 a and 748 b) and a key trackingsignal (communication signal 750) is sent to the delegate entity 508.

While communication signals (706 a, 706 b, 710 a, 710 b, 714 a, 714 b,722 a, 722 b, 726 a, 726 b, 728, 732, 738 b, 738 b, 748 a, 748 b) usedin synchronization between the twin server 506 and the owner device 502are shown, not all of these communication signals are necessary for theoperation of the key sharing process via the twin server 506.Communication signals 730 and 734 are needed in order to allow the ownerdevice 502 to be aware of the key request and to create or approve of ashared digital key (box 734).

While the above disclosure has been described with reference toexemplary embodiments, it will be understood by those skilled in the artthat various changes may be made and equivalents may be substituted forelements thereof without departing from its scope. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the disclosure without departing from the essentialscope thereof. Therefore, it is intended that the present disclosure notbe limited to the particular embodiments disclosed, but will include allembodiments falling within the scope thereof

What is claimed is:
 1. A method of sharing a digital key for a vehicle,comprising: sending a request for a key sharing session from a firstdigital key device to a vehicle server, the first digital key devicehaving a digital key stored thereon; commencing the key sharing sessionat the vehicle server; sharing the digital key from the first digitalkey device to a second digital key device; and ending the key sharingsession at the vehicle server.
 2. The method of claim 1, furthercomprising granting, via the vehicle server, exclusive rights to thefirst digital key device to share the digital key during the key sharingsession.
 3. The method of claim 1, further comprising sharing thedigital key by tracking active entitlements for the digital key.
 4. Themethod of claim 1, wherein the first digital key device is a delegatedevice, further comprising registering digital key stored on thedelegate device at the vehicle.
 5. The method of claim 4, wherein thedigital key stored on the delegate device includes a certificateincluding an owner signature from an owner device that entitles thedelegate device to share the digital key.
 6. The method of claim 5,wherein registering the digital key stored on the delegate device at thevehicle further comprises verifying the owner signature from the digitalkey.
 7. The method of claim 1, further comprising establishing a digitaltwin of the first digital key device at a twin server and sharing thedigital key using the digital twin at the twin server.
 8. The method ofclaim 7, further comprising sending a key sharing request from the twinserver to the first digital key device, creating a shared digital key atthe first digital key device and sending the shared digital key from thefirst digital key device to the twin server, wherein the twin serversends the shared digital key to the second digital key device.
 9. Themethod of claim 1, further comprising using the shared key at the seconddigital key device to perform an operation at the vehicle.
 10. A systemfor sharing a digital key for a vehicle, comprising: a first digital keydevice having a digital key stored thereon; a second digital key device;and a vehicle server configured to commence a key sharing session inresponse to a request from the first digital key device and to end thekey sharing session; wherein the first digital key device shares thedigital key to the second digital key device during the key sharingsession.
 11. The system of claim 10, wherein the vehicle server isconfigured to grant exclusive rights to the first digital key device toshare the digital key during the key sharing session.
 12. The system ofclaim 10, wherein the vehicle server is configured to track activeentitlements for the digital key.
 13. The system of claim 10, whereinthe first digital key device is a delegate device and the vehicle serveris configured to register the digital key stored on the delegate deviceat the vehicle.
 14. The system of claim 13, wherein the digital keystored on the delegate device includes a certificate including an ownersignature from an owner device that entitles the delegate device toshare the digital key.
 15. The system of claim 14, wherein the vehicleis configured to register the delegate device by verifying the ownersignature from the digital key stored on the delegate device.
 16. Thesystem of claim 10, further comprising a twin server configured toestablish a digital twin of the first digital key device and share thedigital key using the digital twin.
 17. The system of claim 16, whereinthe twin server is configured to send a key sharing request to the firstdigital key device and the first digital key device is configured tocreate a shared digital key and send the shared digital key to the twinserver in response to the key sharing request, wherein the twin serversends the shared digital key to the second digital key device.
 18. Thesystem of claim 10, wherein the second digital key device is configuredto use the shared key to perform an operation the vehicle.